In one known type of equipment rack two side plates are interconnected by top and bottom transverse members to form an open-ended box structure. A vertical bus member divides the box structure internally into two compartments. One of the compartments is itself divided into bays each of which is adapted to accommodate a modular specific function circuit unit or card. Each such unit can be slid into or out of its associated bay. In its fully inserted position electrical contacts on the rear of the unit connect directly with electrical contacts on the vertical bus member. Connector units plug into the other side of the bus unit and are accommodated in the other compartment of the box-like structure.
A disadvantage of this known arrangement is that there is no flexibility in the way that the specific function units and the connector units can be interconnected, i.e. the whole arrangement is tailored to a specific requirement because of the constraints imposed by the vertical bus design positioned physically between the specific function units and the connector units.
In another known type of equipment rack instead of a vertical bus member which divides the box-like structure into two compartments there is a horizontal bus member which extends between the two side plates but does not divide the box-like structure into two compartments.
In this second arrangement the electrical connections between the units and the bus member are by means of ribbon connectors. Whilst this second arrangement gives more flexibility than the first arrangement it does have the disadvantages that there is a significant capacitance and consequent signal degradation due to the ribbon connections and a potential failure or at least a degradation in performance of the equipment due to the relatively large numbers of electrical connecting points or contacts involved.
The present invention is concerned with providing equipment rack arrangement which is an improvement on the above discussed prior art arrangements and which is particularly suitable where digital signalling and wide bandwidth analogue employed which demands that more stringent performance criteria have to be met than is the case with analogue signalling.